1. Field of the Invention
The field of the invention is related to apparatus for adjusting the torsional output of a flexible member and in particular to an apparatus for automatically adjusting the torsional output of a flexural pivot.
2. Description of the Prior Art
Flexible pivots such as the flexural pivots exemplified by U.S. Pat. Nos. 3,813,089 (Troeger) 3,811,665 (Seelig), 3,319,951 (Seelig) and 3,142,888 (Troeger) have found wide acceptance in industrial and commercial applications. The flexural pivots of the type disclosed in the above patents comprises two generally cylindrical members tandemly arranged which are capable of rotating with respect to each other about a common axis. The two cylindrical members are internally interconnected by flexure members, generally in a cruciform arrangment. The torque or rotational force generated by a flexural pivot is a function of several parameters, such as the rotational displacement angle between the two cylindrical members, the internal diameter of the cylindrical members and the physical shape and characteristics of the interconnecting flexure elements.
Many applications of these flexural pivots require that they have specified spring rates at predetermined intervals of angular rotation. This spring rate is normally defined as an output torque or force generated by the flexural pivot at one or more predetermined angular displacements between the two cylindrical members.
Quality control of the manufacturing processes of the flexural pivot is capable of controlling the pivot's spring rate within nominal limits. However for a relatively large number of applications these nominal limits are too broad. In order to meet the spring rate requirement for these special applications, the past practice has been to test each flexural pivot produced and select only those having the desired spring rate. The testing and selecting process was slow and tedious and required that a considerable number of pivots be made to obtain the number having the desired spring rate. The disclosed apparatus provides a method for simultaneously testing and adjusting the spring rate of the flexural pivots to meet the predetermined specifications.